The purpose of Core C is to provide state-of-the-art measurements of reactive oxygen species (ROS), reduced glutathione (GSH), glutathione disulfide (GSSG), oxidative modifications of cysteine residues of redox-sensitive proteins in cells, tissues and membranes for participants of the PPG. Core C will assist with preparation and processing of various biological samples for analysis using Electron Spin Resonance (ESR) spectroscopy, High Perfonnance Liquid Chromatography (HPLC) and nano-LC MS/MS analysis. This Core facility has existed since 1999 and has supported numerous studies of superoxide (O2*), hydrogen peroxide (H2O2) and NO in vascular cells and tissue, and it was an essential part of the previous program project studies by Drs. Harrison, Griendling, Taylor and Jo (1-10). This facility will significantly enhance the work of the individual laboratories. and will enhance collaborations between participants of the PPG